The present disclosure relates to an image reading device, a housing of a carriage and a carriage shielding an imaging part from a flare light.
An image reading device includes an optical scanning unit, such as a carriage, to irradiate a document by a light source, to reflect a reflected light from the document by a reflecting mirror and to make the reflected light incident on an imaging lens along an optical axial direction of the imaging lens. The imaging lens captures an incident light onto an imaging part, such as a charge coupled device (CCD). The imaging part picks up an image by photoelectrically converting the reflected light from the document captured by the imaging lens to generate image data.
For example, there is an image reading device configured so that the light source, reflecting mirror, imaging lens and imaging part are incorporated into a carriage in a body and the carriage is scanned to read the image of the document. Since such a carriage is generally manufactured to have tolerance, it is necessary to adjust the incorporation so as to appropriately capture the reflected light from the document onto the imaging part. Therefore, the imaging lens is fixed to a housing of the carriage by a pressuring member, such as a plate spring, after a position in the optical axial direction of the imaging lens is adjusted in order to appropriately adjust magnification.
For example, the reflected light from the document via the reflecting mirrors is varied in accordance with combination of the reflecting mirrors or an attached position. For instance, as shown in FIG. 9, the reflected light in a carriage 101 may become a light Lx forming the image on an imaging lens 102 at a position relatively farther from an imaging part 103 or a light Ly forming the image on the imaging lens 102 at another position relatively nearer to the imaging part 103. In a case where the former light Lx is generated, the imaging lens needs to be adjusted in a direction X separating from the imaging part 103. In another case where the latter light Ly is generated, the imaging lens needs to be adjusted in another direction Y approaching the imaging part 103.
However, in a configuration that the position of the imaging lens 102 can be adjusted, as shown in FIGS. 10 and 11, a gap in the periphery 104 of the imaging lens 102 is easily occurred. If a light Lz passing through (leaked out from) the gap without passing through the imaging lens 102 is incident to the imaging part 103, a received light quantity in the imaging part 103 is heightened at a place irradiated with such a unnecessary incident light Lz (a flare light) and appropriate image data of the document cannot be obtained. Therefore, in the image reading device, it is necessary to provide a configuration of shielding the imaging part 103 from the incident of the light not passing through the imaging lens.
For example, as the image reading device, there is an image reading unit including a light shielding member having a through hole between a lens and a CCD so that an internal shape of the through hole is determined smaller than an external shape of a barrel of the lens.
Moreover, as the image reading device, there is a configuration of providing a reception part formed in a U-shaped section or a V-shaped section in a housing in order to attach a cylinder like formed imaging lens. In this configuration, since a gap is occurred between the U-shaped or V-shaped reception part and imaging lens, it is necessary to close this gap and to shield the unnecessary light to the imaging part.
For example, as the image reading device, there is a configuration that a lens barrel is made of a difference cylinder like formed barrel having an incident side barrel part and a downstream side barrel part, a diameter of the incident side barrel part is smaller than a diameter of the downstream side barrel part, and the lens barrel is attached to a roughly semicircular barrel installed part in a housing. In a rectangular case of a rear part of the housing, a pair of light shielding walls are formed to be vertically suspended downward from an upper end at a center part of a front face vertical wall and to connect to an end part of the barrel installed part at an lower end side. An interval between the light shielding walls is smaller than the diameter of the downstream side barrel part, and then, the light shielding walls are configured so as to shield a flare light run from the outside of the lens barrel to a CCD sensor.
However, in a configuration of capturing the light onto the imaging part via the through hole of the light shielding member by the imaging lens as the above-mentioned image reading unit, when the imaging lens is moved in the optical axial direction in order to adjust the magnification, the interval between the imaging lens and light shielding member is varied. Accordingly, there are possibilities that an optical path from the imaging lens to the imaging part cannot be appropriately secured and the light run from the periphery of the imaging lens to the imaging part cannot be appropriately shielded. Alternatively, it is necessary to provide a light shielding member moving together with the imaging lens during the magnification adjustment, and therefore, the structure may be complicated and manufacturing cost may be increased.
Moreover, since the recent imaging lens is miniaturized, if the barrel diameter in a leading end of the imaging lens is made smaller as the above-mentioned image reading device, the pressuring member hits on this leading end when the imaging lens is fixed to the housing, thereby destabilizing pressuring balance. Accordingly, there is a possibility that the position adjustment of the imaging lens becomes difficult. When the leading end with a small diameter in the imaging lens is lengthened, the pressuring member easily hits on the leading end. On the other hand, when the leading end in the imaging lens is shortened, the imaging lens comes off the light shielding walls, thereby becoming impossible to shield the flare light.